1 /*
2 * MCE grading rules.
3 * Copyright 2008, 2009 Intel Corporation.
4 *
5 * This program is free software; you can redistribute it and/or
6 * modify it under the terms of the GNU General Public License
7 * as published by the Free Software Foundation; version 2
8 * of the License.
9 *
10 * Author: Andi Kleen
11 */
12 #include <linux/kernel.h>
13 #include <linux/seq_file.h>
14 #include <linux/init.h>
15 #include <linux/debugfs.h>
16 #include <asm/mce.h>
17
18 #include "mce-internal.h"
19
20 /*
21 * Grade an mce by severity. In general the most severe ones are processed
22 * first. Since there are quite a lot of combinations test the bits in a
23 * table-driven way. The rules are simply processed in order, first
24 * match wins.
25 *
26 * Note this is only used for machine check exceptions, the corrected
27 * errors use much simpler rules. The exceptions still check for the corrected
28 * errors, but only to leave them alone for the CMCI handler (except for
29 * panic situations)
30 */
31
32 enum context { IN_KERNEL = 1, IN_USER = 2 };
33 enum ser { SER_REQUIRED = 1, NO_SER = 2 };
34 enum exception { EXCP_CONTEXT = 1, NO_EXCP = 2 };
35
36 static struct severity {
37 u64 mask;
38 u64 result;
39 unsigned char sev;
40 unsigned char mcgmask;
41 unsigned char mcgres;
42 unsigned char ser;
43 unsigned char context;
44 unsigned char excp;
45 unsigned char covered;
46 char *msg;
47 } severities[] = {
48 #define MCESEV(s, m, c...) { .sev = MCE_ ## s ## _SEVERITY, .msg = m, ## c }
49 #define KERNEL .context = IN_KERNEL
50 #define USER .context = IN_USER
51 #define SER .ser = SER_REQUIRED
52 #define NOSER .ser = NO_SER
53 #define EXCP .excp = EXCP_CONTEXT
54 #define NOEXCP .excp = NO_EXCP
55 #define BITCLR(x) .mask = x, .result = 0
56 #define BITSET(x) .mask = x, .result = x
57 #define MCGMASK(x, y) .mcgmask = x, .mcgres = y
58 #define MASK(x, y) .mask = x, .result = y
59 #define MCI_UC_S (MCI_STATUS_UC|MCI_STATUS_S)
60 #define MCI_UC_SAR (MCI_STATUS_UC|MCI_STATUS_S|MCI_STATUS_AR)
61 #define MCI_ADDR (MCI_STATUS_ADDRV|MCI_STATUS_MISCV)
62
63 MCESEV(
64 NO, "Invalid",
65 BITCLR(MCI_STATUS_VAL)
66 ),
67 MCESEV(
68 NO, "Not enabled",
69 EXCP, BITCLR(MCI_STATUS_EN)
70 ),
71 MCESEV(
72 PANIC, "Processor context corrupt",
73 BITSET(MCI_STATUS_PCC)
74 ),
75 /* When MCIP is not set something is very confused */
76 MCESEV(
77 PANIC, "MCIP not set in MCA handler",
78 EXCP, MCGMASK(MCG_STATUS_MCIP, 0)
79 ),
80 /* Neither return not error IP -- no chance to recover -> PANIC */
81 MCESEV(
82 PANIC, "Neither restart nor error IP",
83 EXCP, MCGMASK(MCG_STATUS_RIPV|MCG_STATUS_EIPV, 0)
84 ),
85 MCESEV(
86 PANIC, "In kernel and no restart IP",
87 EXCP, KERNEL, MCGMASK(MCG_STATUS_RIPV, 0)
88 ),
89 MCESEV(
90 DEFERRED, "Deferred error",
91 NOSER, MASK(MCI_STATUS_UC|MCI_STATUS_DEFERRED|MCI_STATUS_POISON, MCI_STATUS_DEFERRED)
92 ),
93 MCESEV(
94 KEEP, "Corrected error",
95 NOSER, BITCLR(MCI_STATUS_UC)
96 ),
97
98 /* ignore OVER for UCNA */
99 MCESEV(
100 UCNA, "Uncorrected no action required",
101 SER, MASK(MCI_UC_SAR, MCI_STATUS_UC)
102 ),
103 MCESEV(
104 PANIC, "Illegal combination (UCNA with AR=1)",
105 SER,
106 MASK(MCI_STATUS_OVER|MCI_UC_SAR, MCI_STATUS_UC|MCI_STATUS_AR)
107 ),
108 MCESEV(
109 KEEP, "Non signalled machine check",
110 SER, BITCLR(MCI_STATUS_S)
111 ),
112
113 MCESEV(
114 PANIC, "Action required with lost events",
115 SER, BITSET(MCI_STATUS_OVER|MCI_UC_SAR)
116 ),
117
118 /* known AR MCACODs: */
119 #ifdef CONFIG_MEMORY_FAILURE
120 MCESEV(
121 KEEP, "Action required but unaffected thread is continuable",
122 SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCI_ADDR, MCI_UC_SAR|MCI_ADDR),
123 MCGMASK(MCG_STATUS_RIPV|MCG_STATUS_EIPV, MCG_STATUS_RIPV)
124 ),
125 MCESEV(
126 AR, "Action required: data load error in a user process",
127 SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCI_ADDR|MCACOD, MCI_UC_SAR|MCI_ADDR|MCACOD_DATA),
128 USER
129 ),
130 MCESEV(
131 AR, "Action required: instruction fetch error in a user process",
132 SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCI_ADDR|MCACOD, MCI_UC_SAR|MCI_ADDR|MCACOD_INSTR),
133 USER
134 ),
135 #endif
136 MCESEV(
137 PANIC, "Action required: unknown MCACOD",
138 SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR, MCI_UC_SAR)
139 ),
140
141 /* known AO MCACODs: */
142 MCESEV(
143 AO, "Action optional: memory scrubbing error",
144 SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCACOD_SCRUBMSK, MCI_UC_S|MCACOD_SCRUB)
145 ),
146 MCESEV(
147 AO, "Action optional: last level cache writeback error",
148 SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR|MCACOD, MCI_UC_S|MCACOD_L3WB)
149 ),
150 MCESEV(
151 SOME, "Action optional: unknown MCACOD",
152 SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR, MCI_UC_S)
153 ),
154 MCESEV(
155 SOME, "Action optional with lost events",
156 SER, MASK(MCI_STATUS_OVER|MCI_UC_SAR, MCI_STATUS_OVER|MCI_UC_S)
157 ),
158
159 MCESEV(
160 PANIC, "Overflowed uncorrected",
161 BITSET(MCI_STATUS_OVER|MCI_STATUS_UC)
162 ),
163 MCESEV(
164 UC, "Uncorrected",
165 BITSET(MCI_STATUS_UC)
166 ),
167 MCESEV(
168 SOME, "No match",
169 BITSET(0)
170 ) /* always matches. keep at end */
171 };
172
173 /*
174 * If mcgstatus indicated that ip/cs on the stack were
175 * no good, then "m->cs" will be zero and we will have
176 * to assume the worst case (IN_KERNEL) as we actually
177 * have no idea what we were executing when the machine
178 * check hit.
179 * If we do have a good "m->cs" (or a faked one in the
180 * case we were executing in VM86 mode) we can use it to
181 * distinguish an exception taken in user from from one
182 * taken in the kernel.
183 */
error_context(struct mce * m)184 static int error_context(struct mce *m)
185 {
186 return ((m->cs & 3) == 3) ? IN_USER : IN_KERNEL;
187 }
188
189 /*
190 * See AMD Error Scope Hierarchy table in a newer BKDG. For example
191 * 49125_15h_Models_30h-3Fh_BKDG.pdf, section "RAS Features"
192 */
mce_severity_amd(struct mce * m,int tolerant,char ** msg,bool is_excp)193 static int mce_severity_amd(struct mce *m, int tolerant, char **msg, bool is_excp)
194 {
195 enum context ctx = error_context(m);
196
197 /* Processor Context Corrupt, no need to fumble too much, die! */
198 if (m->status & MCI_STATUS_PCC)
199 return MCE_PANIC_SEVERITY;
200
201 if (m->status & MCI_STATUS_UC) {
202
203 /*
204 * On older systems where overflow_recov flag is not present, we
205 * should simply panic if an error overflow occurs. If
206 * overflow_recov flag is present and set, then software can try
207 * to at least kill process to prolong system operation.
208 */
209 if (mce_flags.overflow_recov) {
210 /* software can try to contain */
211 if (!(m->mcgstatus & MCG_STATUS_RIPV) && (ctx == IN_KERNEL))
212 return MCE_PANIC_SEVERITY;
213
214 /* kill current process */
215 return MCE_AR_SEVERITY;
216 } else {
217 /* at least one error was not logged */
218 if (m->status & MCI_STATUS_OVER)
219 return MCE_PANIC_SEVERITY;
220 }
221
222 /*
223 * For any other case, return MCE_UC_SEVERITY so that we log the
224 * error and exit #MC handler.
225 */
226 return MCE_UC_SEVERITY;
227 }
228
229 /*
230 * deferred error: poll handler catches these and adds to mce_ring so
231 * memory-failure can take recovery actions.
232 */
233 if (m->status & MCI_STATUS_DEFERRED)
234 return MCE_DEFERRED_SEVERITY;
235
236 /*
237 * corrected error: poll handler catches these and passes responsibility
238 * of decoding the error to EDAC
239 */
240 return MCE_KEEP_SEVERITY;
241 }
242
mce_severity_intel(struct mce * m,int tolerant,char ** msg,bool is_excp)243 static int mce_severity_intel(struct mce *m, int tolerant, char **msg, bool is_excp)
244 {
245 enum exception excp = (is_excp ? EXCP_CONTEXT : NO_EXCP);
246 enum context ctx = error_context(m);
247 struct severity *s;
248
249 for (s = severities;; s++) {
250 if ((m->status & s->mask) != s->result)
251 continue;
252 if ((m->mcgstatus & s->mcgmask) != s->mcgres)
253 continue;
254 if (s->ser == SER_REQUIRED && !mca_cfg.ser)
255 continue;
256 if (s->ser == NO_SER && mca_cfg.ser)
257 continue;
258 if (s->context && ctx != s->context)
259 continue;
260 if (s->excp && excp != s->excp)
261 continue;
262 if (msg)
263 *msg = s->msg;
264 s->covered = 1;
265 if (s->sev >= MCE_UC_SEVERITY && ctx == IN_KERNEL) {
266 if (panic_on_oops || tolerant < 1)
267 return MCE_PANIC_SEVERITY;
268 }
269 return s->sev;
270 }
271 }
272
273 /* Default to mce_severity_intel */
274 int (*mce_severity)(struct mce *m, int tolerant, char **msg, bool is_excp) =
275 mce_severity_intel;
276
mcheck_vendor_init_severity(void)277 void __init mcheck_vendor_init_severity(void)
278 {
279 if (boot_cpu_data.x86_vendor == X86_VENDOR_AMD)
280 mce_severity = mce_severity_amd;
281 }
282
283 #ifdef CONFIG_DEBUG_FS
s_start(struct seq_file * f,loff_t * pos)284 static void *s_start(struct seq_file *f, loff_t *pos)
285 {
286 if (*pos >= ARRAY_SIZE(severities))
287 return NULL;
288 return &severities[*pos];
289 }
290
s_next(struct seq_file * f,void * data,loff_t * pos)291 static void *s_next(struct seq_file *f, void *data, loff_t *pos)
292 {
293 if (++(*pos) >= ARRAY_SIZE(severities))
294 return NULL;
295 return &severities[*pos];
296 }
297
s_stop(struct seq_file * f,void * data)298 static void s_stop(struct seq_file *f, void *data)
299 {
300 }
301
s_show(struct seq_file * f,void * data)302 static int s_show(struct seq_file *f, void *data)
303 {
304 struct severity *ser = data;
305 seq_printf(f, "%d\t%s\n", ser->covered, ser->msg);
306 return 0;
307 }
308
309 static const struct seq_operations severities_seq_ops = {
310 .start = s_start,
311 .next = s_next,
312 .stop = s_stop,
313 .show = s_show,
314 };
315
severities_coverage_open(struct inode * inode,struct file * file)316 static int severities_coverage_open(struct inode *inode, struct file *file)
317 {
318 return seq_open(file, &severities_seq_ops);
319 }
320
severities_coverage_write(struct file * file,const char __user * ubuf,size_t count,loff_t * ppos)321 static ssize_t severities_coverage_write(struct file *file,
322 const char __user *ubuf,
323 size_t count, loff_t *ppos)
324 {
325 int i;
326 for (i = 0; i < ARRAY_SIZE(severities); i++)
327 severities[i].covered = 0;
328 return count;
329 }
330
331 static const struct file_operations severities_coverage_fops = {
332 .open = severities_coverage_open,
333 .release = seq_release,
334 .read = seq_read,
335 .write = severities_coverage_write,
336 .llseek = seq_lseek,
337 };
338
severities_debugfs_init(void)339 static int __init severities_debugfs_init(void)
340 {
341 struct dentry *dmce, *fsev;
342
343 dmce = mce_get_debugfs_dir();
344 if (!dmce)
345 goto err_out;
346
347 fsev = debugfs_create_file("severities-coverage", 0444, dmce, NULL,
348 &severities_coverage_fops);
349 if (!fsev)
350 goto err_out;
351
352 return 0;
353
354 err_out:
355 return -ENOMEM;
356 }
357 late_initcall(severities_debugfs_init);
358 #endif /* CONFIG_DEBUG_FS */
359